Many versions of toggle lever tightening devices, particularly for use by the automotive industry in the construction of car bodies are known. Some such toggle lever tightening devices are represented and described, for example, in German Utility Model 93 11 131 U1 and in European Patent Publication EP 0 636 449 B1. In the automotive industry, efforts have been made to reduce the weight of tools such as toggle lever tightening devices by the use of light metals. For this reason, efforts have been made to not construct the housings, i.e., the grip head and the cylinder, of toggle lever tightening devices from steel, as was previously the case. Rather, these portions of the device are being constructed from light metal alloys, in particular aluminum alloys. Such lighter toggle lever tightening devices are used particularly in mobile installations. Since, in the course of tightening the grip head it must absorb large reactive forces, there is a concern that the housing walls will be deformed when light metals are used. More particularly, the concern is that, after a period of use, an accurate tightening position and defined tightening forces will no longer be transmitted.
If, in addition, the toggle lever tightening device is of the type in which a tightening arm is provided on only one side, large axial and radial forces are exerted on the seating, which can lead to twisting of the toggle lever tightening device, which then becomes unusable.
A tightening device can be found in U.S. Pat. No. 4,905,973, whose shaft, which is fixed in place in the housing, is seated by means of a radial and an axial bearing, respectively, in both end areas. A device corresponding to a support plate is provided against which the toggle lever arrangement can be supported in the area of top dead center.
German Patent Publication DE 196 16 441 C1 shows a toggle lever tightening device for use in automobile body construction having a grip head which is rectangular in a cross section and is orthogonal with the longitudinal axis of the piston rod. This device is constructed of two housing elements and has a cylinder adjoining the end of the grip head as an axial extension. The cylinder has a piston which can be pressurized alternately on both sides by a pressure medium, such as air pressure. The piston is sealed, guided and displaceable in the longitudinal direction. When the pistons extend, the piston rod extends through the cylinder and a hollow chamber of the grip head where a toggle lever arrangement is fastened to the free end of the piston rod. The toggle lever is connected with a tightening arm having limit switches or respectively positioned sensors in the form of micro-switches, inductive switches, pneumatic switches or sensors, which are integrated in a chamber of the grip head. The switches can be adjusted in relation to each other and are arranged and fastened on a holder which constitutes a cover for them. The holder is in the form of an interrogation cassette, exchangeable as a whole, in the form of a board in the area of a slit in the axial direction of the grip head. The interrogation cassette has a "T"-shaped form in a view from above, with a fastening rail and a flange. This is followed by a profile extending with its longitudinal axis parallel to the longitudinal axis of the piston rod wherein the interrogation cassette is plugged in from all four sides, in particular from the back, of the housing of the grip head through a narrow slit extending in the direction of the longitudinal axis of the piston rod. The capability of adding on the toggle lever tightening arrangement is maintained in such a way that the profile seals the joints of the slit toward the outside to the greatest possible extent. This toggle lever tightening arrangement is intended to attain the object of being capable of being installed on the device elements, not only from the rear, but also from all four sides while keeping the advantages known from cassette technology.
A toggle lever tightening arrangement with a grip head and a cylinder joining it in the axial extension, is also known from European Patent Publication EP 0 370 914 A1. In this publication, the piston is guided, is longitudinally displaceable and is sealed. The piston can be pressurized alternately on both sides, with pressure from a pressure medium and extends axially with a piston rod through the cylinder and a hollow chamber in the grip head. A toggle lever arrangement is fastened to the free end of the piston rod and is coupled with a tightening arm arranged on a side of the grip head. This coupling includes a fork-shaped tightening arm seated on both end sections of a shaft wherein the toggle lever arrangement is seated on a shaft fixed in place in the grip head. A support plate is also provided which is arranged resiliently or as an elastic spring.